Ron Roy on sun 15 feb 98
Ultrox is a zirconium silicate - like zircopax and super pax.
I have just been working on a very similar cone 6 glaze to this one - it
has a very low expansion/contraction and was reported shivering on several
bodies - It would be best to test it well before adopting it. It is also
oversupplied with boron and will probably be soft and not very durable.
The boron content is 14.67% - this means the calculated expansion is higher
than indicated - but still very low.
When I check it with the limit formulas I use with B2O3 in unity with the
fluxes it is also way short of alumina and silica.
I should also add that having this much Gerstley Borate in a glaze is not a
good idea - this material is too variable to use that much. When I work on
glazes the upper limit for GB is no more than 20% and even that figure is
high if the glaze is unbalanced - just too much chance even a small
variation will upset the glaze. After that I use a frit to source more
boron if it's needed.
> What is Ultrox? Can something else be substituted?
> This glaze has worked very nicely for a number of years; does not run, very
>pred
> etc.
>
> Periwinkle C/6 oxidation
> Gerst. Borate - 49.0
> EPK - 19.0
> Silica - 37.0
> Soda Ash - 0.2
> Ultrox - 5.0
> Cobalt carb. - 2.5
>
> Denim Blue/purple mix, shows texture underneath, will work at c/5, too.
> >>
Ron Roy
93 Pegasus trail
Scarborough Otario
Canada M1G 3N8
Phone: 416-439-2621
Fax: 416-438-7849
Web page: Home page http://digitalfire.com/education/people/ronroy.htm
Duane Littell on mon 16 feb 98
------------------
Ron,
Ultrox, Ultrox 500, Zircopax, Superpax, =22Kaplanpax=22 etc. are Opacifiers
(10-15=25), as is Tin Oxide(7-10=25). All opacifiers react the same in
engobes/glazes. Tin costs more but is 2x stronger than the Zirconium
Opacifiers. Titanium Dioxide is another source, but tends to effect glaze
color.
Dr. Biz
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